Genus: Juniperus (Junipers)
Genus: Thuja (Cedars)
Idaho species are either monoecious (pollen and seed cones on same plant) or dioecious (pollen cones on one tree or shrub and seed cones on different plants) trees or shrubs. The scale-like or needle-like leaves are either opposite or whorled. Staminate strobili contain broadly peltate stamens bearing 2-6 pollen sacs. Ovulate green to purple strobili bear 2-12 dry to fleshy scales. The flattened, peltate (stalk attached in the middle rather than at the edge of the scale) scales may be opposite or in whorls of three. The scales can be free from each other or fused as in junipers (genus Juniperus). Pollen and ovule strobili are born at the end (terminus) of branchlets. Some seeds are winged. Embryos have 2 to 6 cotyledons. Juvenile leaves may differ from adult leaves.
The members of this genus are monoecious or dioecious evergreen shrubs or small trees which bear scale-like, awl-like or needle-like leaves in 2 (opposite) or 3 (whorled) ranks. The basal portion of the leaf is decurrent (forming tiny wings) on the stem. The branchlets are terete or angled, but not flat like the arborvitaes (genus Thuja). The three to five millimeter (one millimeter = approximately 1/25 of an inch) staminate cones bear up to 16 stamens arranged oppositely or in threes. The stamens are eccentrically peltate and bear three to six pollen sacs. The ovulate cones are composed mostly of 3-8 scales that are opposite or in whorls of three. They are fused and fleshy at maturity. The ovulate or seed bearing cones are often referred to as "juniper berries." The glaucous, blue to brown cones bear 1 to 5 wingless seeds. Each embryo has two to six cotyledons. The indehiscent cones are readily eaten and digested by animals. However, the hard seeds are not digested and are thus disbursed in animal droppings.
General information here.
Key to Family:
KEY TO THE SPECIES OF THE CUPRESSACEAE IN IDAHO
1a. Mature seed cones longer than wide, with flattened, dry, opposite, distinct scales, not berry-like; twigs and branchlets appearing flat rather than round; scale-like leaves opposite in 4 rows.- Western Red Cedar (Thuja plicata Donn.)
1b. Mature seed cones spherical or almost spherical with 3 to 8 fleshy, fused scales, cone berry-like; twigs and branchlets appearing round; scale-like leaves in 2's or 3's. -Junipers (genus Juniperus ):
2a. The needle-like leaves in 3's, 5-19 mm long, not glandular; plant a low shrub less than 2 meters tall.- Common or Mountain Juniper (Juniperus communis L.)
2b. The scale-like leaves in 2's or 3's, less than 7 millimeters long, glandular on back; shrubs or small trees at maturity more than 2 meters tall.
3a. Plant like a small tree with one cental trunk.
4a. Leaves in 3's with a prominent gland on back; seed cone bluish black, 7 to 8 mm in diameter, 1-3 seeded
Plants found in southwestern Idaho Western or Sierra Juniper ( Juniperus occidentalis Hook.)
4b. Leaves in 2's with small gland on the back; seed cone 5-6 mm in diameter, blue, usually one or 2 seeded; throughout Idaho Rocky Mountain Juniper (Juniperus scopulorum) Sarg.